FWIW, I don't mix with it but do track with it. (I mix ITB.)
I especially like it on vocals - I don't think it's as transparent as the RNC, but I like its flava.
I also sometimes do bass through it but it's not my preferred (dbx160XT is, sometimes a 166A, or a Meek VC3Q, followed by the VLA.)
Right now, I'm onna dbx kick for acoustic guitars and so haven't tried that.
Also, damn cool looking, ain't it?
I've not done any mods, but a tube change is said to be audible.